Field of the Invention
The present invention relates to a resin composition, especially a resin composition comprising an alkenyl phenoxy phosphazene component. The present invention also relates to a prepreg and laminate provided by using the resin composition.
Descriptions of the Related Art
Printed circuit boards (PCBs) are circuit substrates that are used for electronic devices to load other electronic components and to electrically connect the components to provide a stable circuit working environment. One kind of conventional printed circuit board is a copper clad laminate (CCL), which is primarily composed of resin(s), reinforcing material(s) and copper foil(s). Examples of resins include epoxy resins, phenolic resins, polyamine formaldehyde resins, silicone resins, and Teflon; and examples of reinforcing materials include glass fiber cloths, glass fiber mats, insulating papers, and linen cloths.
In general, a printed circuit board can be prepared by using the following method: immersing a reinforcing material such as a glass fiber fabric into a resin (such as epoxy resin), and curing the immersed glass fiber fabric into a half-cured state, i.e., B-stage, to obtain a prepreg; superimposing certain layers of the prepregs and superimposing a metal foil on at least one external surface of the superimposed prepregs to provide a superimposed object; hot-pressing the superimposed object, i.e., C-stage, to obtain a metal clad laminate; etching the metal foil on the surface of the metal clad laminate to form a defined circuit pattern; and finally, drilling a plurality of holes on the metal clad laminate and plating these holes with a conductive material to form via holes to accomplish the preparation of the printed circuit board.
In many applications, resin materials require good flame retardance. In some cases, a resin with a flame resistance property such as a halogenated polymer is sufficient to provide the desired flame retardance. If the flame retardance of a resin is insufficient to provide the desired flame retardance, it would be necessary to add a flame retardant into the resin. Known compounds capable of being used as flame retardants include inorganic hydroxides, organic phosphorous compounds, organic halogen compounds, halogen-containing organic phosphorous compounds, etc. However, during the curing process of a resin containing a halogen-containing compound, the halogen-containing compound will generate hydrogen halides through thermal decomposition, and the generated hydrogen halides will corrode molds and adversely affect the properties of the resin and cause discoloration of the resin. Similarly, during the recycling process (e.g., incineration processing) of the product of the cured resin, the halogen-containing compounds will generate biological hazard gases such as hydrogen halides. Hence, halogen-containing compounds do not meet current environmental protection requirements, and halogen-free flame retardants are much in demand.
Phosphorous-containing compounds are one of the most popular halogen-free flame retardants. Examples of phosphorous-containing compounds include triphenyl phosphate (TPP), tricresyl phosphate (TCP), and the like. However, such phosphorous-containing compounds are generally in the form of a liquid or a solid with a low melting point under room temperature and are volatile substances. Hence, they tend to lower the curing temperature of the resins in which they are applied, and cause caking and leakage problems during fluxing.
Applications of phosphorous-containing compounds as flame retardant have been disclosed in many patent documents. U.S. Pat. No. 3,900,444 uses alkali salts of phosphoric acids as flame retardants for polyesters; however, if such phosphorous-containing compounds are applied into resin compositions for preparing printed circuit boards, they tend to adversely affect properties, such as the dielectric constant (Dk), dielectric loss (Df), thermal resistance, moisture resistance and electrical erosion resistance of the laminates thus prepared. U.S. Pat. No. 6,596,893 discloses a phenoxyphosphazene compound used in thermoplastic resins or thermoset resins. U.S. Pat. No. 8,063,245 discloses a phosphazene compound used in photosensitive resins composition. WO 2015/069642 discloses a phosphazene polycarbonate compounds retardant.